NAIROBI, Kenya — Ethiopia declared a state of emergency on Tuesday and called on its citizens to pick up arms and prepare to defend the capital as rebel forces from the northern region of Tigray pressed south toward the city, following the capture of two key towns.
The Tigrayans, who have been fighting the government for the past year, have joined forces with another rebel group as they advance on the capital, Addis Ababa. Foreign officials monitoring the fighting said there were signs that several Ethiopian army units had collapsed or retreated.
The state of emergency reflected the rapidly changing tide in a metastasizing war that threatens to tear apart Ethiopia, Africa’s second-most populous country.
It also marked another dismal turn in the fortunes of Prime Minister Abiy Ahmed, a Nobel Peace Prize winner whose international reputation has been battered by a war that has led to reports of human rights violations, massacres and famine.
Only a year ago, Mr. Abiy launched a military campaign in the northern Tigray region, hoping to vanquish the regional ruling party, the Tigray People’s Liberation Front, his most troublesome political foe. But after promising a swift, even bloodless campaign, Mr. Abiy was quickly drawn into a military quagmire.
The Ethiopian military suffered a major defeat when it was forced to withdraw from Tigray in June. Now the war is rapidly moving toward Mr. Abiy, after the Tigrayan rebels took the towns of Dessie and Kombolcha, just 160 miles to the northeast of the capital, in recent days.
Under the state of emergency declared Tuesday, Mr. Abiy has sweeping powers to arrest and detain critics, impose curfews and restrict the news media. Announcing the measures in a televised news conference, Ethiopia’s justice minister, Gedion Timothewos, said that any citizen over 18 could be called into the fight.
“Those who own weapons will be obliged to hand them over to the government,” he said. The state of emergency will last six months, the government said.
The announcement brought a mixed reaction in the city, where tensions have been building for days as news filtered in of Tigrayan military advances. A taxi driver named Dereje, who refused to give his second name, said he intended to join in the fight.
“I am not going to sit in my house and wait for the enemy,” he said. “I will fight for my kids and country.”
But a teacher, who declined to give his name, said he had lost faith in the government. “They lied to us that T.P.L.F. have been defeated,” he said. “I am terribly worried about what is going to happen. May God help us.”
President Biden, who has threatened to impose sanctions on Ethiopia unless it moves toward peace talks, said Tuesday he would revoke trade privileges to Ethiopia, including duty-free access to the United States, on account of “gross violations of internationally recognized human rights.”
In a separate briefing, Jeffrey Feltman, the Biden administration’s envoy to the Horn of Africa, told reporters the deepening conflict could have “disastrous consequences” for Ethiopia’s unity and its ties to the United States.
Billene Seyoum, a spokeswoman for Mr. Abiy, did not respond to a request for comment.
Simon Marks contributed reporting from Brussels and an employee of The New York Times contributed reporting from Addis Ababa, Ethiopia.